1. Field of the Invention
The present invention relates to an insertion device comprising an operation input portion which maintains a curving state of a curving portion even if a hand is taken off during operation and which returns to a range including a neutral position beyond a predetermined curving operation range.
2. Description of the Related Art
In general, there is an insertion device which comes into a body cavity or into a duct having curved parts for visual observation. This insertion device includes a medical or industrial endoscope device comprising an insertion portion which is elongated and flexible and which is provided with a curving portion at its distal end. For example, when the medical endoscope device is used for a diagnosis or surgery of the body cavity, an operation portion is operated to drive the curving portion provided on the distal side of the insertion portion into the body cavity while vertically and horizontally curving the curving portion.
For example, in an endoscope device disclosed in Patent Literature 1 (Jpn. Pat. Appln. KOKAI Publication No. 2008-264107), a curving portion is coupled to a curving operation portion by an operation wire, and this operation wire is pulled by the curving operation portion to bend the curving portion. In this endoscope device, a curving operation dial which is rotationally operated is used as the curving operation portion, and an operation is input by one (360°) or more rotational operations of the dial.
If the operation dial is configured to be rotated on or more times (360° or more) as in Patent Literature 1 described above, an operator makes a round trip to the rotation direction of the operation dial and then repeats the rotational operations. As a result, the operator finds it difficult to find an original neutral position and know the actual curving state of the curving portion. In this case, the operator returns the operation dial to the neutral position under visual observation, and then again performs a curving operation.
Accordingly, Patent Literature 2 (Jpn. Pat. Appln. KOKAI Publication No. 2009-226125) has suggested an operation portion of an endoscope device comprising an urging mechanism which returns an UD (up/down) or RL (right/left) operation dial of the operation portion to a neutral position. The operation portion has the urging mechanism in which two spiral springs that are wound in opposite directions face each other and have their inner ends attached to a rotating shaft of the operation dial and their outer ends attached to a fixed member. In this urging mechanism, the elastic forces (urging forces) of the springs are adjusted to balance at the neutral position (initial position: a curving portion linearly extends) of the operation dial. If the operation dial is rotated in this configuration, one of the springs expands its spiral, while the other spring shrinks its spiral. As a result of these actions, the operation dial returns to the original neutral position which is the initial position in response to each of the springs when a hand is taken off the operation dial.